| Internet-Draft | PCEP-SR-YANG | October 2024 |
| Li, et al. | Expires 22 April 2025 | [Page] |
This document augments a YANG data model for the management of Path Computation Element Communications Protocol (PCEP) for communications between a Path Computation Client (PCC) and a Path Computation Element (PCE), or between two PCEs in support for Segment Routing in IPv6 (SRv6) and SR Policy. The data model includes configuration data and state data (status information and counters for the collection of statistics).¶
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Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 22 April 2025.¶
Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
The Path Computation Element (PCE) defined in [RFC4655] is an entity that is capable of computing a network path or route based on a network graph, and applying computational constraints. A Path Computation Client (PCC) may make requests to a PCE for paths to be computed.¶
PCEP is the communication protocol between a PCC and PCE and is defined in [RFC5440]. PCEP interactions include path computation requests and path computation replies as well as notifications of specific states related to the use of a PCE in the context of Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE). [RFC8231] specifies extensions to PCEP to enable stateful control of MPLS TE LSPs.¶
[RFC9603] extends [RFC8664] to support SR for IPv6 data plane.¶
[I-D.ietf-pce-pcep-yang] defines a YANG [RFC7950] data model for the management of PCEP speakers. This document contains a specification of the PCEP-SRv6 YANG module, "ietf-pcep-srv6" which provides the PCEP-SRv6 [RFC9603] data model. This document also contains the PCEP SR Policy YANG module, "ietf-pcep-srpolicy" which provides a reference to SR Policies [RFC9256].¶
The PCEP operational state is included in the same tree as the PCEP configuration consistent with Network Management Datastore Architecture (NMDA) [RFC8342]. The origin of the data is indicated as per the origin metadata annotation.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
This document also uses the following terms defined in [RFC7420]:¶
PCEP entity: a local PCEP speaker.¶
PCEP peer: a remote PCEP speaker.¶
PCEP speaker: where it is not necessary to distinguish between local and remote.¶
Further, this document also uses the following terms defined in [RFC8231] :¶
Stateful PCE, Passive Stateful PCE, Active Stateful PCE.¶
Delegation, Revocation, Redelegation.¶
LSP State Report, Path Computation Report message (PCRpt).¶
LSP State Update, Path Computation Update message (PCUpd).¶
PCE-initiated LSP, Path Computation LSP Initiate Message (PCInitiate).¶
Path Setup Type (PST).¶
Segment Routing (SR).¶
Segment Routing in IPv6 (SRv6).¶
SR Policy.¶
A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is defined in [RFC8340].¶
In this document, names of data nodes and other data model objects are often used without a prefix, as long as it is clear from the context in which the YANG module each name is defined. Otherwise, names are prefixed using the standard prefix associated with the corresponding YANG module, as shown in Table 1.¶
| Prefix | YANG module | Reference |
|---|---|---|
| inet | ietf-inet-types | [RFC6991] |
| te-types | ietf-te-types | [RFC8776] |
| pcep | ietf-pcep | [I-D.ietf-pce-pcep-yang] |
| srv6-types | ietf-srv6-types | [I-D.ietf-spring-srv6-yang] |
| sr-policy-types | ietf-sr-policy-types | [I-D.ietf-spring-sr-policy-yang] |
The following additional documents are referenced in the model defined in this document -¶
| Title | Reference |
|---|---|
| Path Computation Element Communication Protocol (PCEP) Extensions for IPv6 Segment Routing | [RFC9603] |
| Carrying Binding Label/Segment Identifier (SID) in PCE-based Networks | [RFC9604] |
| Segment Routing Policy Architecture | [RFC9256] |
| PCEP Extensions for Signaling Multipath Information | [I-D.ietf-pce-multipath] |
| PCEP extension to support Segment Routing Policy Candidate Paths | [I-D.ietf-pce-segment-routing-policy-cp] |
[I-D.ietf-pce-multipath] defines a mechanism to encode multiple paths for a single set of objectives and constraints. This is a generic PCEP mechanism, not specific to any path setup type or dataplane but the key usecase is SR.¶
Further discussion is needed on how to model it in PCEP YANG.¶
The PCEP-SRv6 YANG module defined in this document has all the common building blocks for the PCEP-SRv6 extension. The model augments PCEP capabilities at the Entity and peer level with SRv6 capability in PCEP, support for NAI, MSD and the SID structure. The model also extends the LSP in the LSP-DB to maintain SRv6 paths.¶
module: ietf-pcep-srv6
augment /pcep:pcep/pcep:entity/pcep:capabilities:
+--rw srv6 {srv6}?
| +--rw enabled? boolean
| +--rw nai? boolean
| +--ro srv6-msd* [msd-type]
| +--ro msd-type uint8
| +--ro msd-value? uint8
+--rw sid-str {sid-str}?
+--rw lb? uint8
+--rw ln? uint8
+--rw fn? uint8
+--rw an? uint8
augment /pcep:pcep/pcep:entity/pcep:peers/pcep:peer/pcep:capabilities:
+--rw srv6 {srv6}?
+--rw enabled? boolean
+--rw nai? boolean
+--ro srv6-msd* [msd-type]
+--ro msd-type uint8
+--ro msd-value? uint8
augment /pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp:
+--ro srv6 {srv6}?
+--ro segment-list
+--ro segment* [index]
+--ro index uint32
+--ro sid-value? srv6-types:srv6-sid
+--ro sid-str {sid-str}?
| +--ro lb? uint8
| +--ro ln? uint8
| +--ro fn? uint8
| +--ro an? uint8
+--ro endpoint-behavior? identityref
¶
The PCEP-SRPolicy YANG module defined in this document has all the common building blocks for the PCEP-SR Policy extension. The model augments the LSP in the LSPDB to have information refering to the SR Policy and the candidate path.¶
module: ietf-pcep-srpolicy
augment /pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp:
+--ro sr-policy
+--ro headend? inet:ip-address-no-zone
+--ro color? uint32
+--ro endpoint? inet:ip-address-no-zone
+--ro name? string
+--ro cp
+--ro protocol-origin? identityref
+--ro originator? string
+--ro discriminator? uint32
+--ro name? string
¶
The sr-policy container is applicable for both SR-MPLS and SRv6.¶
RFC Ed.: In this section, replace all occurrences of 'XXXX' with the actual RFC number and all occurrences of the revision date below with the date of RFC publication (and remove this note).¶
<CODE BEGINS> file "[email protected]" module ietf-pcep-srv6 { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-srv6"; prefix pcep-srv6; import ietf-srv6-types { prefix srv6-types; reference "I-D.ietf-spring-srv6-yang: YANG Data Model for SRv6 Base and Static"; } import ietf-te-types { prefix te-types; reference "RFC 8776: Common YANG Data Types for Traffic Engineering"; } import ietf-pcep { prefix pcep; reference "I-D.ietf-pce-pcep-yang: A YANG Data Model for Path Computation Element Communications Protocol (PCEP)"; } organization "IETF PCE (Path Computation Element) Working Group"; contact "WG Web: <https://datatracker.ietf.org/wg/pce/> WG List: <mailto:[email protected]> Editor: Cheng Li <mailto:[email protected]> Shuping Peng <mailto:[email protected]>"; description "The YANG module augments the Path Computation Element Communications Protocol (PCEP) YANG operational model with Segment Routing in IPv6 (SRv6). Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2024-10-19 { description "Initial revision."; reference "RFC XXXX: A YANG Data Model for Segment Routing (SR) Policy and SRv6 support in Path Computation Element Communications Protocol (PCEP)"; } /* Features */ feature srv6 { description "Support Segment Routing in IPv6 (SRv6) for PCE."; reference "RFC 9603: Path Computation Element Communication Protocol (PCEP) Extensions for IPv6 Segment Routing"; } feature bsid { description "Support Binding SID for PCE."; reference "RFC 9604: Carrying Binding Label/SID in PCE-Based Networks"; } feature sid-str { description "Support for SID Structure"; reference "RFC 9603: Path Computation Element Communication Protocol (PCEP) Extensions for IPv6 Segment Routing"; } /* Identity */ identity path-setup-srv6 { if-feature "srv6"; base te-types:path-signaling-type; description "SRv6 path setup type"; } /* Groupings */ grouping srv6-msd { description "SRv6 MSD"; leaf msd-type { type uint8; description "SRv6 Maximum Segment Depth (MSD) Type"; } leaf msd-value { type uint8; description "SRv6 MSD value for the type"; } reference "RFC 9603: Path Computation Element Communication Protocol (PCEP) Extensions for IPv6 Segment Routing"; } grouping srv6 { description "SRv6"; container srv6 { if-feature "srv6"; description "If SRv6 is supported"; leaf enabled { type boolean; description "Enabled or Disabled; set to true when Enabled"; } leaf nai { type boolean; default "false"; description "True indicates capability to resolve Node or Adjacency Identifier (NAI) to SRv6 Segment Identifier (SID)"; } list srv6-msd { key "msd-type"; config false; description "list of SRv6 MSD"; uses srv6-msd; } } } grouping segment-list { description "Segment list grouping"; container segment-list { description "Segments for given segment list"; list segment { key "index"; description "Configure Segment/hop at the index"; uses segment-properties; } } } grouping segment-properties { description "Segment properties grouping"; leaf index { type uint32; description "Segment index"; } leaf sid-value { type srv6-types:srv6-sid; description "SRv6 SID value"; } uses sid-str; leaf endpoint-behavior { type identityref { base srv6-types:srv6-endpoint-type; } description "The behavior associated with the SRv6 SIDs."; } /*Query: Add NAI?*/ } grouping sid-str { description "The default SID Structure"; container sid-str { if-feature "sid-str"; description "The default SID Structure"; leaf lb { type uint8; description "SRv6 SID Locator Block length in bits"; } leaf ln { type uint8; description "SRv6 SID Locator Node length in bits"; } leaf fn { type uint8; description "SRv6 SID Function length in bits"; } leaf an { type uint8; description "SRv6 SID Arguments length in bits"; } } } /* * Augment modules to add SRv6 */ augment "/pcep:pcep/pcep:entity/pcep:capabilities" { description "Augmenting SRv6 capabilities"; uses srv6; uses sid-str; } augment "/pcep:pcep/pcep:entity/pcep:peers/pcep:peer" + "/pcep:capabilities" { description "Augmenting SRv6 capabilities for peer"; uses srv6; } augment "/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp" { description "Augmenting SRv6 for LSP"; container srv6 { when "derived-from-or-self (/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst, 'path-setup-srv6')" { description "For SRv6 path"; } if-feature "srv6"; uses segment-list; description "SRv6 information"; } } } <CODE ENDS>¶
RFC Ed.: In this section, replace all occurrences of 'XXXX' with the actual RFC number and all occurrences of the revision date below with the date of RFC publication (and remove this note).¶
<CODE BEGINS> file "[email protected]" module ietf-pcep-srpolicy { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-srpolicy"; prefix pcep-srp; import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-te-types { prefix te-types; reference "RFC 8776: Common YANG Data Types for Traffic Engineering"; } import ietf-pcep { prefix pcep; reference "I-D.ietf-pce-pcep-yang: A YANG Data Model for Path Computation Element Communications Protocol (PCEP)"; } import ietf-sr-policy-types { prefix sr-policy-types; reference "I-D.ietf-spring-sr-policy-yang: YANG Data Model for Segment Routing Policy"; } organization "IETF PCE (Path Computation Element) Working Group"; contact "WG Web: <https://datatracker.ietf.org/wg/pce/> WG List: <mailto:[email protected]> Editor: Cheng Li <mailto:[email protected]> Shuping Peng <mailto:[email protected]>"; description "The YANG module augments the Path Computation Element Communications Protocol (PCEP) YANG model with Segment Routing (SR) Policy. Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2024-10-19 { description "Initial revision."; reference "RFC XXXX: A YANG Data Model for Segment Routing (SR) Policy and SRv6 support in Path Computation Element Communications Protocol (PCEP)"; } /* Features */ feature multipath { description "Support for multipath ERO."; reference "I-D.ietf-pce-multipath: PCEP Extensions for Signaling Multipath Information"; } /* Identities */ identity sr-policy { base te-types:association-type; description "SR Policy Association"; reference "I-D.ietf-pce-segment-routing-policy-cp: PCEP extension to support Segment Routing Policy Candidate Paths"; } /* Groupings */ grouping sr-policy { description "Segment Routing Policy grouping"; leaf headend { type inet:ip-address-no-zone; description "SR Policy headend"; reference "RFC 9256: Segment Routing Policy Architecture"; } leaf color { type uint32 { range "1..max"; } description "SR Policy Color"; reference "RFC 9256: Segment Routing Policy Architecture"; } leaf endpoint { type inet:ip-address-no-zone; description "SR Policy Endpoint"; reference "RFC 9256: Segment Routing Policy Architecture"; } leaf name { type string; description "SR Policy name"; reference "RFC 9256: Segment Routing Policy Architecture"; } } grouping sr-policy-cp { description "Segment Routing Policy Candidate Path grouping"; leaf protocol-origin { type identityref { base sr-policy-types:protocol-origin-type; } description "SR Policy Candidate Path Protocol"; reference "RFC 9256: Segment Routing Policy Architecture"; } leaf originator { type string; description "SR Policy Candidate Path Originator"; reference "RFC 9256: Segment Routing Policy Architecture"; } leaf discriminator { type uint32 { range "1..max"; } description "SR Policy Candidate Path Discriminator"; reference "RFC 9256: Segment Routing Policy Architecture"; } leaf name { type string; description "SR Policy Candidate Path name"; reference "RFC 9256: Segment Routing Policy Architecture"; } } augment "/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp" { description "Augmenting SR Policy"; container sr-policy { when "derived-from-or-self (/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst, 'path-setup-sr') or derived-from-or-self (/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst, 'path-setup-srv6')" { description "Applicable for SR or SRv6"; } uses sr-policy; container cp { uses sr-policy-cp; description "SR Policy Candidate Path information"; } description "SR Policy information"; } } } <CODE ENDS>¶
The YANG module defined in this document is designed to be accessed via network management protocol such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer and the mandatory-to-implement secure transport is SSH [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]¶
The NETCONF access control model [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a pre-configured subset of all available NETCONF or RESTCONF protocol operations and content.¶
There are a number of data nodes defined in the YANG module which are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., <edit-config>) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability:¶
/pcep:pcep/pcep:entity/pcep:capabilities/pcep-srv6:srv6 - configure local SRv6 capability and parameters.¶
/pcep:pcep/pcep:entity/pcep:peers/pcep:peer/pcep:capabilities/pcep-srv6:srv6 - configure peer's SRv6 capability and parameters.¶
Unauthorized access to above list can adversely affect the PCEP session between the local entity and the peers. This may lead to inability to compute new paths, stateful operations on the delegated as well as PCE-initiated LSPs.¶
Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability:¶
/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep-srv6:srv6 - The SRv6 SID in the network. Unauthorized access to this could provide entire path and network usage information.¶
/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep-srpolicy:sr-policy - The reference to SR Policy. Unauthorized access to this could provide SR Policy usage information.¶
This document registers a URI in the "IETF XML Registry" [RFC3688]. Following the format in RFC 3688, the following registration has been made.¶
This document registers a YANG module in the "YANG Module Names" registry [RFC6020].¶
Name: ietf-pcep-srv6
Namespace: urn:ietf:params:xml:ns:yang:ietf-pcep-srv6
Prefix: pcep-srv6
Reference: This I-D
Name: ietf-pcep-srpolicy
Namespace: urn:ietf:params:xml:ns:yang:ietf-pcep-srpolicy
Prefix: pcep-srp
Reference: This I-D
¶
The authors would like to thank Dhruv Dhody for the initial YANG model.¶